In the field of moving materials, it is often necessary to move bulk materials such as grain, sand, or other bulk material having small particle size. While the bulk materials can be moved by mechanical means, such as shovels, conveyer belts, and such where the device moving the bulk materials carries the bulk material from one location to another location these methods can be impractical and risk contaminating the bulk material. The simplest method for moving such bulk materials is to use gravity. An outlet located at the bottom of the container or bin containing the bulk material is opened and the bulk material is allowed to flow out. While this method is very useful, the bulk material must first be raised into the container or bin so that gravity can act upon it. Typically, the movement provided by gravity is limited and at some time the bulk material must again be raised to a position that gravity can again act on the bulk material.
Blower packages are also used in soil remediation and other processes.
It has become common to move such bulk materials using airflow to carry the material from one location to another location within a conduit. This method is referred to as pneumatic conveying. This method is especially useful as the conduit can be routed in a fashion that occupies, or requires very little space.
In the processing of bulk material having relatively small particle size, the bulk material must frequently be moved from one location to another quickly and efficiently. A commonly used method is to inject compressed air or gas into the conduit at the beginning of the system to push the bulk material through the conduit. This method is commonly referred to as dilute-phase, pressure, pneumatic conveying. Using either of these methods, the bulk material can be moved horizontally or vertically over some distance quickly and efficiently. Another commonly used method is to evacuate a container that is connected to the conduit at the end of the system, drawing air or gas through the conduit to pull the bulk material through the conduit. This method is commonly referred to as dilute-phase, vacuum, pneumatic conveying.
To move the bulk material in a dilute-phase, pressure, pneumatic conveying system, a blower must produce a sufficient volume of compressed air at a sufficient pressure to move the bulk material and keep the bulk material moving in the conduit. Similarly, in a dilute-phase, vacuum, pneumatic conveying system, to move bulk material, a blower package must remove sufficient volume of air to produce a sufficient vacuum to move the bulk material and keep the bulk material moving in the conduit. When the volume and/or pressure or vacuum of air is insufficient to keep the bulk material moving, the conduit can become obstructed as the bulk material settles from the air stream and is no longer being moved. An obstructed conduit creates a stoppage of flow which usually requires the intervention of workers to clear and would thus slow if not stop the transfer process, if not other processes that depend from the transfer process.
While the use of airflow to move bulk materials is efficient, it is not without problems. Blower packages used are often very large assemblies of components including: A structural base, an inlet filter/silencer, outlet filter/silencer, blower, motor, drive, drive guard, piping & fittings, and support brackets all assembled in an unsanitary, exposed fashion. One of the primary problems is that the blower package is very noisy. Most blower packages create sufficient noise that they must be housed in a separate room so that the sound does not injure the employees. Separate rooms create additional expense of the building, use more floor space, and require longer piping to provide or evacuate the air from the point of use. Longer piping results in greater airflow restriction which, directly results in wasted energy consumption over the useful life of the system.
Much of the blower noise is caused rapid movement of air through the blower and by the mechanical action of the blower acting upon the air. The mechanical noise of displacing the air often is transmitted through both the inlet and outlet of the blower to connecting piping, then radiates to the exterior environment. Conventional wisdom has been to use chambered silencers or absorptive filters to absorb the sound waves coming from the blower. While this method does reduce noise, it all too often does not sufficiently reduce the noise to allow the blower package to be placed in an occupied space. Additionally, a large percentage of the noise radiates from the blower housing and can only be reduced by some means of secondary containment that permits air to flow in contact with the blower housing to dissipate heat, generated by its operation.
Placement of a blower in a separate building, while removing the noise from the occupied area, causes increased pressure losses and a reduction in the volume of air produced by the blower. Frequently the loss of pressure and volume is sufficient so that a larger blower and/or greater horsepower motor must be used thereby increasing costs and energy requirements.